test: add regression test for 51586

Signed-off-by: Matteo Collina <[email protected]>
PR-URL: #51491
Reviewed-By: Vinícius Lourenço Claro Cardoso <[email protected]>
Reviewed-By: Marco Ippolito <[email protected]>
Reviewed-By: Matthew Aitken <[email protected]>
Reviewed-By: Rafael Gonzaga <[email protected]>
Reviewed-By: Moshe Atlow <[email protected]>
Reviewed-By: Franziska Hinkelmann <[email protected]>
Reviewed-By: Benjamin Gruenbaum <[email protected]>

test/parallel/test-webstream-structured-clone-no-leftovers.mjs

@@ -0,0 +1,28 @@
+import '../common/index.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert';
+
+test('do not leak promises', async () => {
+  const buf = new Uint8Array(1);
+  const readable = new ReadableStream({
+    start(controller) {
+      controller.enqueue(buf);
+      controller.close();
+    }
+  });
+
+  const [out1, out2] = readable.tee();
+  const cloned = structuredClone(out2, { transfer: [out2] });
+
+  for await (const chunk of cloned) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+
+  for await (const chunk of out2) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+
+  for await (const chunk of out1) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+});